Right, to access www.your-domain.tld you need to set up either an A record or CNAME pointing to it. Your password issue is perplexing though. I'm having a hard time imagining what would cause that! I'd suggest redirecting the www subdomain back to the main one, as it's usually a good idea to pick one or the other either way.

Since you're using Rails, I imagine you're also using Nginx? Edit your configuration to add a new server block that sets up a redirect from www to the root domain. It would look something like:

server {

    listen       80;

    server_name  www.your-domain.tld;

    return       301 http://your-domain.tld$request_uri;

}



server {

    listen       80;

    server_name  your-domain.tld;

    # And whatever else....

}